package OLDSTUFF.ClassAlgebra;

/**
 * Class for representin the empty an empty-expression object.
 * This is equivalent to the empty set.
 * @author Martin Haulrich
 */
public class EmptyExpression implements Expression {

    public final static int type = Expression.EMPTY;


    @Override
    public int type() {
        return type;
    }


    @Override
    public String toString() {
        //return "\u2205";
        return "Ø";
    }


    @Override
    public boolean equals(Object o) {

        return (o instanceof EmptyExpression);
    }


    @Override
    public int hashCode() {
        // -12 is arbitrary
        return -12;
    }
}
